Michał Nazarewicz schrieb:
On Mon, 26 Apr 2010 22:14:54 +0200, Josua Dietze
<digidietze@xxxxxxxxxxxxxxx> wrote:
Important for the Linux handling is that "mode 1" is clearly
distinguishable from "mode 2", either by using a different product ID
or by setting a different class for the device or interface 0 (will
most likely be "8" for the install mode).
So it will be enough to change the USB device class for the zeroth
interface for udev to recognise the mass storage to be ejected? Note
that I will use mass storage in the second mode as well.
This is often the case with the common "zero-cd" devices, but
they have the storage on upper interface numbers after switching.
The point is to enable udev or any other tool to distinguish
between "unswitched" and "switched"; otherwise the procedure
for switching will be executed on *both* modes which might
disturb the device or the system.
A change in one of the attributes like iProduct or iSerial
could be detected as well of course.
Also, I think that it might be a good idea to make some "standardised"
mechanism for all such devices so that a generic udev code could be
written. Adding things to the descriptors may be difficult in a way,
but maybe adding "[NoCD]" to the interface name would be enough.
That is up to the (countless) manufacturers of course; on the
other hand, the Windows drivers need to recognize the mode as
well so there should always be one way or the other to
accomplish that.
Josua Dietze
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